Sand filter.



UNITED @AWT oFFICE.

JOHAN n. K. PENNINK, or Aiisrnnnin, NETHERIAXDS.

-SANDFILTEB. i

To all whom it may concern:

Be it known that I, J 0in-ix M. K. PENN'INK, director of `the mimicipal Waterworks of Amsterdam, a subject of the Queen of th Netherlands, residing at 629 Keizersgracht, Amsterdam, in the Kingdom of the Netherlands, have invented certain new and useful Improvements in or Relating to Sand Filters, of which the following is a specification.

It is well known that the biological and more particularly, the bacteriological action of a. sand filter is only satisfactoryr when the upper layer of the sand becomes covered with fine vegetable fibers, the residues of water animalculaa, and the suspended solid matters of the unfiltered water, as in this condition such top covering or layer efectually holds back even the smallest particles in the Water. Indeed it is only when so covered that the filter furnishes pure water and for this reason it is necessary to await the formation of a new covering before again putting the filter in use, each time t-he filter is cleaned, when, of course the old covering is destroyed. This involves much loss of time and water each time the filter is cleaned and such cleaning is always necessary when the coverino` of plankton or algfe becomes less permeable at some parts than is desirable for the filter l then no longer delivers a sufficient volume of water,

or on increasing the pressure of the water in order to force the desired quantity through it, the water delivered decreases in purity as at the higher pressure fine particles are easily carried along.v In order to clean such a filter it is first drained dry, the covering of algze and the uppermost layers of sand lying immediately below it are then removed by paring ofi' with shovels. At the same time destruction of the nextlower layer of sand is unavoidable, as in cleaning the filter such layer is trodden over and barrows or the like are wheeled over it. Furrows, footprints and the like are therefore formed in the upper surface of' such lower layer and finally the whole of the up )er surface or top of the sand has to be raked and turned over before the filter can be again started.

Removing tlle covering of algae by spraying is not desirable for by such a process the upper surface ofthe sand would be still more disturbed than it is by paring it off.

Now according to this invention the efficiency of the filter is increased by facilitating the cleaning operation, the invention having ySpecication of Letters Patent.

Application led October 3, 1907.l ASerial No. 395,755.

reference to an improved method of cleaning suoli fters and to means for this purpose, whereby the necessary cleaning can be effected in a short time by flushing with -water without the flushing water destroying or even touching the active'filtering layer of sand. For this purpose, according to this invention the uppermost layer of sand in the filter is covered with a preferably smooth cloth that lies closely thereon and which is m'ade of a textile material adapted to resist rotting as long as possible, such for example as ramie. 'To assist its resistance to rotting the material of which the cloth is formed is preferably impregnated with a 'suitable medium. The cloth is attached in a suitable manner to the side walls of the filter and is arranged to incline towards the 'middle or towards other points. At the lowest oint or points the cloth is formed with an ori' ce or orifices communicating with a pipe built into the lter bed and into which the end or ends of the cloth at such part around the orifice or orifices freely hang down. This pipe is led out of the filter and is furnished with a device for controlling the flow of water therethrough.

The use of cloths in filters has already been tried, in sach cases however the cloth formed a preliminary filten and was arranged se arately from thesand layer so that it acte( in a similar manner to a sand filter. For this purpose it was' kept rough to facilitate a covering of aigre forming in and upon it. 'hen this covering became too thick, the cloth had to be washed out whereby the covering of algre was entirely destroyed. The cloth so arranged therefore suffers from the vsame disadvantage as-a sand filter and after each cleaning *will only work properly when a new filtering skin has formed upon the cleaned cloth- The arrangement of the cloth according to this invention differs from that heretofore proposed in that it lies closely upon the sand ayer. The covering of algze forms very quickly, first in the upper sand layer, and then on the underside of the cloth between the fibers thereof, and finally upon the cloth itself; in this way the covering of algre lying upon the layer of sand, which would otherwise be iiable to destruction by water animalculse places, and to become cracked, is efiieiently protected by the cloth lying over it. The covering of formed under, in and upen the cloth will therefore be much Patented Aug. 4, 190s,

:moredurable and consequently .the bacteriological action of t-he filter will be increased.

A further advantage of the'clloth covering is that the covering of algze, when it has become insufficiently permeable, can be removed as far as necessary by simplyflushing thecloth with Water without touching the upper layers of sand.

igure 1 of the accompanying drawing shows in vertical longitudinal section a construetional example of yfiltering plant embodying this inventior. Fig. 2 is a plan of the filter bed. Fig. 3 illustrates'an arrangement of the cloth covers for larger filter basins.

Upon the filter bed 2, which consists Vof pebbles, sand etc. and which is placed in the filter basin 1 in the usual way, is laid a' cloth cover 3 formed of an impregnated textile material such for example as ramie. The outer edges of the cloth 3 are detachably connected on all sides to the 'side Walls of the basin 1 for which purpose the cloth edges are preferably laid upon a ledge 4 and held thereon by stones 5 or the like.

In its center the cloth cover has a tubular `outlet 6, by which it is suspendedin the upper end of a vertical ipe 7 that runs downwardly through the fi ter basin, and under it to a part where it is provided with a shut oi valve or other device S. The draw off pipes 9 for the filtered pure Water are arranged in the usual Way on the floor of the filter basin and communicate at one side or on both sides with a common pipe 10, see Fig. 2.

Should the filter bed be too large-for a single cloth it is advisable to use several such cloths, -as indicated at 11 in Fig. 3, the several cloths being connected together with good joints and each being provided with a central draw off pi )e 12.

The working of the filter is as follows: After the formation of the filter bed 2 from the various layers of pebbles and sand )laced in the filter basin 1, the cloth cover 3 1s laid upon the upper l; yer and secured to the ledges 4; the central tubular branch 6 is caused to hang down in the mouth of the vertical pipe 7 and the joint therewith is made properly tight. Then the cock S is closed the unfiltered water is delivered to the filter, filtration and formation of the covering of algae then takes place in a very short time under, in and above, the clot-h covering 3.

Should the covering of algae become so insufliciently permeable that the removal thereof is necessary the unfiltered Watersupply is shut off and thecock 8 'is opened. All the unfiltered water in the filter basin vvill then suddenly run out and carry'ayvay with it the entire covering of algae lying on the top of the cloth 3 without even touching or disturbing the layer of sand lying immefirst remove the cove] ing of icedia'tely underneath the clothf ny algze residues still remaining can be detached from 'the cloth by spraying With water and consequently also removed. Should it be necessary toalsewemove the algae adhering'to theunderside of tdmtlpure'ivater can be forced in through the pi )es 9. i A gentle kstream of water will there y, be caused to flow along the underside of the cloth 3 so as to -carry the superfluous algae with it down into the draw ofl` pipe 7 Without .disturbing the upper layers of sand.

For the purpose of cleaning the cloth cover -it may be completely taken off and washed elsewhere but in all these operations the upper layer of sand is not distufoed. Villiere as formerly the operation of cleaning took several days it can, as betere described, be now accomplished in as many hour-sand with much less expenditure of labor. In winter,

when the filters are frozen over, the filtering skin can be Washed away without having to After being cleaned the filter is at Once ready for use again.

Existing sand filtering plants can be readily adapted for cleaning according to this inven- 1 tion without material alteration.

That I'claim is:

1. In a sand filter, a filter basin, afilter bed therein, a filter cloth lying closely on the -top layer of sand forming said filter bed and formed with an opening, a conduit with which 'the openinor of said cloth communica'tes and means for controlling at will the lpassage through said conduit.

2. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely onthe top layer of sand forming said filter bed and formed with an o iening, means for securing the outer edges o said cloth to the sides of said filter basin, a conduit with which the opening of said cloth communicates and means for controlling at Will the passage through said conduit.

3. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer of sand forming said filter bed and formed With an opening, a ledge on the side walls ot said basin above said filter bed, means for securing the outer edges of said cloth on said ledge, a conduit with which the opening of said cloth communicates and means for controlling at ill the passage Athrough said conduit.

4. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer of sand forming said filter bed andl formed with an opening, a conduit, with which the o ening in said cloth communicates, exten( ing vertically through said filter bed and through the bottom of said filter basin., and means for controlling at will the passage through said conduit.

therein, a filter cloth lying closely on the top layer of sand forming said filter bed and formed with an opening, a conduit with which the opening of said cloth communicates, and a valve for controlling at will the passage through said conduit.

7 In a sand filter, a filterbasin, a filter bed therein, a-filter cloth lying closely on the top layer of sand forming said filter bed and formed with an opening, a vertical conduit into the mouth of which extend the edges of the said cloth around the opening thereof, and means for controlling at will the passage through said conduit.

S. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer of sand forming said filter bed and formed with an opening, a conduit with which the opening of said cloth communicates, means for spraying water on the upper surface of said cloth, and means for controlling at will thepassage through said conduit.

9. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer of sand forming said filter bed and formed with an opening, a conduit with which the opening of said cloth communicates, means for controlling at will the passage through said conduit, and means for .forcing pure water into said filter bed below said cloth.

10. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closel on the top layer of sand forming said filter ed andv formed with an opening, a conduit 'with which the opening of said cloth commumf cares, means for controlling at will the passage through said conduit and pipes arranged in said filter bed at approximately threel fourths of the height thereof adapted to de- 6. In a sand filter, a filter basin, a filter bed lilve pure water into said filter bed below said c ot i.

11. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer ofsand forming said filter bed and depending towards a part lower than the re-V mainder in which )art an opening is formed, a conduit with w iich the opening y,of said cloth communicates and means for,control ling at will the passage through. said conduit. 12. In a sand filter, a filter basin, a filter bed therein, a number of -filter cloths lyin closely on the top layer of sand forming sai lter bed and each formed with an opening, conduits with which the openings of said filter cloths communicate, and means for controlling at will the passage through said 13. In a sand filter, a filter basin, a filter bed therein, a filter cloth lying closely on the top layer of sand forming said filter bed and depending towards a part lower than the remainder in which. part .an opening is formed,

means for securing the outer edges of said nesses.

JOHAN M.,K. PENNINK.

Witnesses:

THOMAS H. VERHAUL, AN'roNIE ELBERTS DOYER. 

